Method of recovering manganese steel.



1,291,656. No Drawing. Continuation of application Serial Nos. $1,118,filed UNITED STATES PATENT OFFICE.

, 'WESLEY G. NICHOLS, OF CHICAGO HEIGHTS, ILLINOIS, ASSIGNOR TO AMERICANMANGANESE STEEL COMPANY, 0F CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

METHOD or RECOVERING'MANGANESE STEEL.

Specification of Letters Patent.

PatentedJ an. 144, April 14, 191d, and 152,107, filed March 2, 1917,This application filed May 31, 1918. Serial No. 237,426.

To all whom it may concern.

' Be it known that I, l/VESLEY GJ Nlonons,

a citizen of the United States, residin at Chicago Heights, in thecounty of (look and State of Illinois, have invented certain new anduseful Improvements in Methods.

of Recovering Manganese Steel, of which the following is aspecification.

This invention relates to the method of recovering or reusing manganesesteel available from scrap or other sources of steel which containsmanganese in suflicient proportions to render the ,steel of especial;

value, and the invention has for its primary object to provide a methodof melting such steel witha minimum loss of its manganese content, andthus maintaining the essential characterof the steel as a manganesesteel and adapting it ,for commercialdelivery as such, if desired, or sofar reducing the loss of the manganese in the remelting as to. effectgreat" saving in the quantity of this element that must 'be added incase the recovered manganese, steel is to be incorporated into, orusedfor alloying with, a body of blown metal in the production of a newand larger heat of manganese steel.

The presentv application is acontinuation of my application SerialNumber 152,107, filed Marchfl, 1917, and of my application Serial Number91,118, filed April 14, 1916'.-

In the following specification, the term manganese steel, except wherethe context otherwise indicates, will be used to denote steel showingamanganese content of some percentage commercially recognized aslend-"ing partlcular character to the steel. Such steel usually shows amanganese content of from 11 to 14% and a carbon'content of from 1.1to1.4%.- The term blown metal will be usedto denote decarburized iron,

such, for instance, as the metal in the bath.

resulting from thecompleted Bessemer operation in a converter.Form-manganese denotes the commercial product usually containing on anaverage of 80% manganese,

' 6% carbon, and -10 to 12% iron.

It has long been recognized that owing to the ready oxidation andevenlva orization of manganese, that occur at the igh temperaturesattained in blown metal, the now exceedingly valuable manganese elementex-- isting in considerable quantities in scrap ing-over steel and-entirely-lost if the manganese'scrap 1s blown with the charge, of

.material delivered to the converter. Various proposals have been madefor avoiding this loss. These have generally been along the lines ofcontrolling the environment in which the manganese steel is melted, witha view to excluding oxidizing influences as far as practicable;utilizing a covering of basic slag or the like to protect the metal bathfrom such oxygen as cannot be excluded from the furnace; supplyingsubstances more readily oxidizable than manganese, and thereby consumingthe limited amount of oxygen that does gain access to the bath; andsupplying substances that will reduce a portion of the oxidizedmanganese. that may have been takenlup by the slag, and therebyreturning the manganese to the bath.

But allthese methods involve able features, and succeed but' partially,if

at all. In most of them the temperature is excessive at the sourceofheat employed (for instance, the electric are), if' not throughout theentire bath, so thatbxidation and even vaporization of the contained.manganese takes place at least on the surface ofthe scrap, or in theimmediate presence of the heat source, if not throughout the bath,besides involving undesirable expenditure for counteracting materialsand objectionprolonging the time required for the tr'eatment. -None ofthem, so far as I am aware,

has attained the success in retaining the nlangaiiese that is insuredby'my' present invention, which avoids the difiiculties mentioned,reduces to a minimum the oxidation the skin of these chunks of scrapwill become,

fluid quite rapidly and the manganese will have opportunity to oxidizeor to unite with the slag. The addition ofreducing agents to the slagwill serve to precipitate the manganese but it will also make. necessarythe decarburization' of the steel as the carbon content will change. Todecarburize the steel necessarily involves a high temperatureandconsequent loss of manganese.

While proceeding upon lines Whicl'rmaintain a non-oxidizing environmentfor the bath, so far as the same may be obtained by inclosing the bath,covering with basic slag, and the like, the underlying feature of myprocess resides in controlling the temperature of the source of heat andthrough the temperature of the source, regulating the temperatures underwhich the proceeding takes place, so that not only is the bath as awhole prevented from reaching vaporizing or even oxidiz ing temperaturesduring the melting, but no part of the bath or of the fragments of scrapis subjected to any such temperature in advance of the whole body ofmetal; on the contrary, the temperature of the heat source and of thebath is developed in stages, and the manganese lying upon the surface ofthe 7 pieces of scrap or in the immediate presence of the arc isprotected equally with that contained on the interior of the pieces, orthroughout the entire bath. At the final heat stage, which may besu'fiicient to induce oxidation, precautions willhave been taken toalford the greatest possible protection to the metal, and thetemperaturewill exist only for the shortest time, being developed immediatelypreceding the drawing of the furnace,

"In carrying out the invention, an electric furnace is'preferablyemployed because of the facility with which atmosphere can beexcludedtherefrom, but any other method of heating which combines thefeature of excluding oxidizing influences with controlled temperature ofthe heat source may be employed.

Having charged the furnace with the scrap or other form of manganesesteel, care is exercised to avoid a temperature at the arc in excess of1200 F. until the entire bath has reached that temperature, and untilmeans have been provided or are ready for application to protect againstoxidation under the menace further increase of temperature. Even thetemperature ofi1200 F. is preferably approached gradually or in stages,by first using even a lower temperature in the arc and developing thesame throughout the bath and gradually-increasing the temperature of theare or heat source, and in this way working up to 1200 F. In thepreferred procedure, an initial temperature stage as low as 600 F. mayfirst be developed with advantage, as by charging cold scrap into a coldfurnace and developing an are at such voltage as will produce a heat ofsubstantially 600 F, and maintaining this heat until the whole body ofthe metal is at a homogeneous temperature. Preferably the electrode isso adjusted as to permit the creation of an are of as short length as ispossible and to bring the are into closeproximity with the scrap. Thevoltage being low assures the conduction of energy of not too vigorousaction, which will prevent any but etc., up to 1200 F. Or, if thefurnace has not fully cooled down from a previous heat, but stands at atemperature of, say 1500 F., after having been opened and had necessaryrepairs made to its lining, the cold scrap may be charged into thefurnace, by which time the temperature will have fallen to 600 or 700F., then the furnace is closed and'permitted to stand closed withoutapplication of additional heat until the charge has absorbed heat fromthe walls of the furnace and been brought to an initial temperature of,say 500 F., after which the are will be developed with restrictedvoltage to create a temperature equal to that of the scrap and furnace.c. 500F.,'and then developed in successive stages of temperature,

which will gradually work the heat of the bath through 600, 700, etc.,up to 1200 F.

At 1200 F. the charge of manganese steel ging fluxes for production ofwhich, may be added either at this stage or at an earlier stage, or evenat the time of charging the furnace or partly at the time of chargingand partly as the increased temperature stages are attained ifobservation shows the covering of slag to be insufficient. Up to thistemperature, 2'. e. 1200 F. serious oxidation of the m'agnanese will nottake place;

much less will there have been much less by vaporization.

The temperature of the bath is raised gradually or in stages toapproximately 1200 F. and above 1200 F. in like manner, in the sensethat the temperature of the heat source is controlled, and, therefore,the temperature in any one part materially in excess of that of thewhole bath is carefully avoided until it reaches about 2400 F. at

\ which manganese steel is completely fused,

made into a pouring ladle for casting into billets, or molds, or fortransfer to and alloying with a heat of blown metal; In the latterinstance additional manganese will be added, as explained below. K g

When the metal is ready to be tapped, the

' temperature maybe cautiously increased above substantially 2400 Fl torender the bath highly fluid, but this increase will be relativelyharmless because the bath is now well protected, and the increasedtemperature will .exist for but a short time.

I have found that by proceeding as above outlined the loss of manganesein the reuse of manganese steel scrap will be reduced to a very smallpercentage of the original "manganese content, and, indeed, to such asmall percentage as w1ll permit the reuse of the manganese steel assuch, and without restoring any of its manganese content. However, therestoration of the proportion of manganese can be readily accomplished aby charging into the furnace a' suitable quantity of vferro-manganese,the quantity of which is readily estimated because the analysis of themanganese steel scrap originally charged is accurately known, and itsloss of manganesehas been so well controlled that it will be of aconstant and readily estimated small percentage.

Ifthe bath of manganese steel obtained as above described is to be usedfor alloying a larger body of blown metal, for instance, in theproduction of manganese steel, it will, of course, 'be necessary to adda suitable percentage of. ferro-manganese. The addition of manganese forthis purpose can be made in the same furnace with the melted scrap andat a temperature stage that will prac-' tically avoid loss by oxidation.Thus a very great saving in this now expensive alloying element will beeffected, and the use of a separate furnace and the firing and laborcost of serving the same will be avoided.

I .do not claim in this application the method of producing manganesesteel by the use of the subject-matter of the present application, asthis is described and claimed in my application Serial Number 151,882,filed March 2, I917.

What I claim is: I,

1. The improvement in the art of recovering manganese steel, whichconsists in applying heat to the steel. at an initial temperature belowthe-oxidizing temperature of manganese, and'at successively increasingstages of temperature until theentire mass is gradually brought to themelting point of manganese steel.

2. The improvement in theart 'of recovering manganese'steel, whichconsists in applying heat to the steel at ap initial temperature below.the oxidizing temperature of manganese, and at SIICOBSSIVGly' increasingstages of temperature until the entire mass is gradually brought to themelting point of'manganese steel; the process being carried on in arelatively inert environment.

3. The improvement in the art of recovering manganese steel, whichconsists in applying heat to the steel at an initial temperature belowthe oxidizing temperature of manganese, and at successively increasingstages of temperature until the entire mass is gradually brought to themelting point of manganese steel; the process being carried on in arelatively inert environment, and the presence of a protecting coveringfor the bath being insured by the time the bath at-'.

tains the melting'temperature.

4. The improvement in the art of recovering manganese steel, whichconsists in applying heat to the steel at an initial temperature belowthe oxidizing temperature of manganese, and at successively increasingstages of temperature until the entire mass is gradually brought to themelting point of.

manganese steel; the bath being maintained at about the meltingtemperature until the metal isneeded, and the temperature beingincreased to the point of high fluidity of the metal immediatelypreceding the tapping of the furnace. 1 I

5. The improvement in the art of reco'v ering manganese steel, whichconsists inheating the charge of metal by an initial application of heatnot over 700 F., and then increasing the applied heat instages to bringthe entire mass gradually to the melting point of the steel.

6. The improvement in the art ofrecovering manganese steel, whichconsists in heating the charge of metal by an initial application ofheat not over 700 F., and then increasing the applied heat in stages tobring the ,entire mass gradually to 'the melting point of the steel,maintaining the temperature at about the melting point until the metalis needed, and raising to the temperature of high fluidity just previousto tapp 7. The improvement in the art of recovering manganese steel,which consists'in developing an initial temperature of below 700 F.throughout the charge of metal, gradually increasing the temperature ofthe bath to 1200 F., and thereafter raising the temperature to about2400 F.; the several stages of temperature being developed throughoutthe bath without materially increasing the temperature of any portion ofthe bath beyond that of the remainder thereof.

8. The improvement in the art of recovering manganese steel, Whichconsists in applying heat to the steel at an initial temperature belowthe oxidizing temperature of manganese, and at successively increasingstages of temperature until the entire mass is gradually brought to themelting point of manganese steel; additional -manganese bemembers ingsupplied to the bath in the melting fur- 'nace.

9. The improvement in the art of recovering manganese steel, Whichconsists in applying heat to the steel at an initial temper ature belowthe oxidizing temperature of manganese, and at successively increasingstages of temperature until the entire mass is gradually brought to; themelting point of manganese steel; the bath being maintained at about themelting temperature until the metal is needed, and the temperature beingincreased to the point of high fluidity of the metal immediatelypreceding the tapping of the furnace; additional manganese beingsupplied to the bath in the melting furnace.

Signed at Chicago 'Heights, Illinois, this 26th day of April, 1918.

ESLEY G. NICHOLS.

